method of isomerization of light gasoline fractions

ABSTRACT

The invention relates to isomerization of light gasoline fractions to produce a high octane gasoline component, and may be used in oil refining and petrochemical industries. 
     Isomerization is conducted at a temperature of 100-220° C., pressure—1.0-3.5 MPa, hydrogen:raw material mole ratio=(0.3-10):1, using a catalyst having the following composition, mass-%. 
     
       
         
               
               
               
             
                   
                   
               
                   
                 Group 8A metal 
                 0.1-0.8 
               
                   
                 sulphuric acid ion 
                  4-15 
               
                   
                 composition of metal 
                 to 100 
               
                   
                 oxides 
               
                   
                   
               
           
              
             
             
              
              
              
              
              
             
          
         
       
     
     As the metal of Group 8A platinum and/or palladium, and/or iridium, and/or rhodium, and/or ruthenium are used, and the composition of metal oxides is as follows: 
       xFe 2 O 3 .yMnO 2 .zTiO 2 .nAl 2 O 3 .mZrO 2 ,         with the following mole coefficient values:   x=(0.06-3.6)·10 −3 ;   y=(0.11-2.3)·10 −3 ;   z=(0.12-2.5)·10 −3 ;   n=(7.8-21.5)·10 −2 ;   m=(63.3-74.7)·10 −2 .   m=(63.3-74.7)·10 −2  
 
and a mass ratio of said sulfuric acid ion to said composition of metal oxides is 0.042-0.178. The invention allows increasing a stability of a method of summarization.

The invention relates to isomerization of light gasoline fractions to produce a high octane gasoline component, and may be used in oil-refining and petrochemical industries.

There are known a method for producing a catalyst useful in hydrocarbon isomerization, a catalyst produced by this method and use thereof (Patent RU No. 2 191 627, IPC7 B01J 31/44, 1996). A raw material being isomerized is contacted with a catalyst which is a noble metal selected from platinum, palladium, ruthenium, osmium or iridium on an alumina support, containing up to 20 mass-% of such active components as silicon and titanium dioxides, magnesium or zirconium oxide. The alumina is pre-treated with an aluminium halide compound having a hydrocarbon substituent. The catalyst may be promoted with tin, lead, germanium, bismuth, cobalt, nickel, indium, zinc, uranium, thallium, zirconium or mixtures thereof. Isomerization is conducted at a temperature of 100-200° C. in the presence of hydrogen, where hydrogen: raw material mole ratio is 0.01-5. A gas-raw material mixture is fed on a fixed-bed catalyst under a pressure of 0.2-4.0 MPa.

The disadvantage of this method is low stability of isomerization (concentration of the most branched isomer 2,2-dimethylbutane (2,2-DMB) in the mixture of all hexane isomers decreases after 200 hours of operation from 28 mass-% to 14 mass-%).

Known is a layered catalyst for paraffin isomerization (EP No. 1 002 579, IPC7 B01J 37/02, 1998), a top layer of which comprises platinum in the amount of 0.05-10 mass-1. A catalyst core is a zirconium oxide or a mixture of zirconium and aluminium oxides, containing 0.5-5 mass-% of sulfur. An intermediate layer comprises one of the following metals: Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, preferably Mn, Fe, Ni, in the amount of 0.05-2 mass-%. An atomic ratio of the intermediate layer metal to the top layer metal is more than 3. Isomerization process is conducted at a temperature of 100-200° C. and pressure of 0.03-4 MPa, in the presence of hydrogen (hydrogen:feedstock mole ratio is 0.05-5:1).

The disadvantage of this process of isomerization of light gasoline fractions is low stability of isomerization (concentration of the most branched isomer 2,2-DMB in the mixture of all hexane isomers decreases after 200 hours of operation from 28 mass-1 to 20 mass-%).

The most similar method is isomerization of light gasoline fractions at a temperature of 170-270° C. and pressure of 0.8-4.0 MPa, with hydrogen:raw material mole ratio equal to (0.2-10):1, with the use of a catalyst for isomerization of light paraffin C₄-C₆ hydrocarbons (Patent RU No. 2 171 713, IPC7 B01J 23/40, 2000) containing 0.2-1.0 mass-1 platinum or palladium, 0.05-2.5 mass-% chlorine and 0.5-10 mass-% sulfate-ion, which are deposited on a mixture of aluminium and zirconium oxides. The aluminium oxide being pre-promoted with titanium and manganese used in the following mass ratios TiO:Al₂O₃=0.005-0.05 and MnO₂:Al₂O₃=0.001-0.05.

The disadvantage of this method is low stability of isomerization (concentration of the most branched 2,2-DMB isomer in the mixture of all hexane isomers decreases after 200 hours of operation from 34 mass-1 to 25 mass-%).

The proposed method of isomerization of light gasoline fractions provides a high stability of isomerization.

The method of isomerization of light gasoline fractions is carried out by contacting a raw material with a catalyst containing the following composition of metal oxides: xFe₂O₃.yMnO₂.zTiO₂.nAl₂O₃.mZrO₂, with a hydrogenating component and an oxygen-containing sulphur ion applied thereon, wherein mole coefficients in the composition of oxides are as follows:

x=(0.06-3.6)·10⁻³ ; y=(0.11-2.3)·10⁻³ ; z=(0.12-2.5)·10⁻³ ; n=(7.8-21.5)·10⁻² ; m=(63.3-74.7)·10⁻²,

and a mass ratio of sulphur ion to metal composition is 0.042-0.178.

As the hydrogenating component of the catalyst use is made of a Group 8A metal: platinum and/or palladium, and/or iridium, and/or rhodium, and/or ruthenium, and as the oxygen-containing sulphur ion—a sulphuric acid ion, with the following mass ratio of catalyst components:

Group 8A metal 0.1-0.8 sulphuric acid ion  4-15 metal compositions to 100

The process is conducted at a temperature of 100-220° C. and pressure of 1.0-3.5 MPa, using hydrogen: raw material mole ratio=(0.3-10):1.

Mode of carrying out isomerization process.

A raw material (pentane-hexane fraction) is mixed with a hydrogen-containing gas, maintaining the hydrogen: raw material mole ratio equal to (0.3-10):1. Further, the gas-raw material mixture is heated and supplied to a reactor, where it is brought into contact with the above described catalyst (hourly space velocity 0.5-4 hr⁻¹). In the reactor, isomerization of paraffin hydrocarbons C₅-C₆, hydrogenation of unsaturated and aromatic compounds and partial cracking of hydrocarbons with C₁-C₄ gases formation take place.

Catalyst Preparation.

A composition of metal oxides is prepared by mixing iron, manganese, titanium, zirconium and aluminium hydroxides, maintaining the required mole ratio of oxides, with the following extrusion, drying and calcination at a temperature of 500-900° C.

The obtained composition of metal oxides is impregnated with platinum and/or palladium, and/or iridium, and/or rhodium, and/or ruthenium compound solutions. To provide the required ratio of an oxygen-containing sulphur ion to a composition of oxides a sulphuric acid is added to the impregnating solution. After the impregnation is complete the catalyst is calcinated at a temperature of 400-700° C.

For illustration of this method experiments were carried out for which a continuous flow pilot plant was used.

A catalyst charge was 4 cm³. Isomerization process was conducted using a temperature range of 100-220° C., pressure 1.0-MPa, hourly space velocity (V) 0.5-4.0 hr⁻¹ and a mole ratio of hydrogen:raw material=(0.3-10):1 (Q). As the raw material a hydrofined straight run HK-70° C. gasoline fraction was used, having octane number as determined by F-2 method—67 items of the composition, mass-%:

isobutane 0.01 n-butane 0.31 isopentane 15.41 n-pentane 34.03 cyclopentane 4.20 2,2-dimethylbutane 0.51 2,3-dimethylbutane 1.45 2-methylpentane 14.55 3-methylpentane 7.81 n-hexane 14.92 methylcyclopentane 5.00 cyclohexane 0.47 benzene 1.22 total of C₇ hydrocarbons 0.11 Impurities, ppm sulphur 0.5 water 10 chlorine 1.0 nitrogen 0.5

The reaction products were analyzed by flow gas-liquid chromatography using an OV-101 capillary column with a liquid phase.

Degree of isomerization was assessed by 2,2-DMB proportion in the total amount of hexane isomers.

EXAMPLE 1

Raw material is mixed with hydrogen in a mole ratio of hydrogen to starting material=5, heated to 150° C. and at a hourly space velocity of 2 hr⁻¹ and under a pressure of 2.8 MPa is supplied to a reactor filled with a catalyst having the following composition, mass-%:

platinum 0.3 sulphuric acid ion 9.2 composition of oxides 90.5

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 2

Isomerization process is carried out similarly to that as described in Example 1, except that feed space velocity is 0.5 hr⁻¹, hydrogen:raw material mole ratio is 0.3 and the process is carried out under a pressure of 3.5 MPa and at a temperature of 100° C., using a catalyst having the following composition, mass-%

palladium 0.8 sulphuric acid ion 15.0 composition of oxides 84.2

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 3

Isomerization process is carried out similarly to that as described in Example 1, except that feed space velocity is 4.0 hr⁻¹, hydrogen:raw material mole ratio is 10 and the process is carried out under a pressure of 1.0 MPa and at a temperature of 220° C., using a catalyst having the following composition, mass-%:

iridium 0.6 sulphuric acid ion 15.0 composition of oxides 84.4

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 4

Isomerization process is carried out similarly to that as described in Example 1, except that feed space velocity is 0.5 hr⁻¹, hydrogen:raw material mole ratio is 0.3 and the process is carried out under a pressure of 3.5 MPa and at a temperature of 100° C., using a catalyst having the following composition, mass-%:

rhodium 0.8 sulphuric acid ion 15.0 oxides composition 84.2

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 5

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

ruthenium 0.8 sulphuric acid ion 15.0 composition of oxides 84.2

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 6

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

platinum 0.2 palladium 0.2 sulphuric acid ion 4.0 composition of oxides 95.6

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 7

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

platinum 0.2 iridium 0.3 sulphuric acid ion 8.6 composition of oxides 90.9

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 8

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-1:

platinum 0.2 rhodium 0.4 sulphuric acid ion 9.5 composition of oxides 89.9

Mole coefficient values in the composition of oxides and a weight ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 9

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

platinum 0.2 ruthenium 0.5 sulphuric acid ion 7.5 composition of oxides 91.8

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 10

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

platinum 0.1 sulphuric acid ion 15.0 composition of oxides 84.9

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 11 Comparative

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

platinum 0.3 sulphuric acid ion 9.2 composition of oxides 90.5

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

Isomerization process in comparative examples 12-20 is carried out similarly to that as described in Example 11.

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 21 Comparative

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

platinum 0.3 sulphuric acid ion 3.8 composition of oxides 95.9

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

EXAMPLE 22 Comparative

Isomerization process is carried out similarly to that as described in Example 1, using a catalyst having the following composition, mass-%:

platinum 0.3 sulphuric acid ion 15.2 composition of oxides 84.5

Mole coefficient values in the composition of oxides and a mass ratio of sulphuric acid ion to composition of oxides are provided in Table 1.

Conditions under which the process is carried out and results are provided in Table 2.

The results which were obtained show high stability of the process of isomerization of light gasoline fractions (Ex. 1-10).

However, these results can be obtained only with the claimed metal oxide mole coefficients in the composition and the claimed ratio of oxygen-containing sulphur ion to composition of metal oxides.

Thus, with lowering mole coefficients of iron (ex. No. 11), manganese (ex. No. 13), titanium (ex. No. 15), zirconium (ex. No. 19) and aluminium (ex. No. 17) oxides 2,2-DMB proportion in the total amount of C₆ isomers decreases after 200 hours of operation by 17.9-21.1.

Increasing mole coefficients of iron (ex. No. 12), manganese (ex. No. 14), titanium (ex. No. 16), aluminium (ex. No. 18) and zirconium (ex. No. 20) oxides above the claimed value decreases stability of isomerization process by 18.8-24.6%.

As to a mass ratio of oxygen-containing sulphur ion to composition of metal oxides, both in the cases of this value decrease (ex. No. 21) or its increase (ex. No. 22) with respect to the claimed range 2,2-DMB proportion in the total amount of C₆ isomers falls by 23-24%.

TABLE 1 Catalyst characteristics Ratio of sulphuric acid ion to Example Oxide mole coefficients composition No. x · 10³ y · 10³ z · 10³ n · 10² m · 10² of oxides  1 1.83 1.2 1.31 14.65 68.85 0.102  2 0.06 1.2 1.31 14.65 68.8 0.178  3 3.6 1.2 1.31 14.65 68.8 0.178  4 1.83 0.11 1.31 14.65 68.8 0.178  5 1.83 1.2 1.31 21.5 63.3 0.042  6 1.83 2.3 1.31 14.65 68.8 0.095  7 1.83 1.2 0.12 14.65 68.8 0.106  8 1.83 1.2 2.5 14.65 68.8 0.082  9 1.83 1.2 1.31 7.8 74.7 0.178 10 1.83 1.2 1.31 14.65 68.8 0.102 11 comp. 0.05 1.2 1.31 14.65 68.8 0.102 12 comp. 3.8 1.2 1.31 14.6 68.8 0.102 13 comp. 1.83 0.09 1.31 14.65 68.8 0.102 14 comp. 1.83 2.5 1.31 14.65 68.8 0.102 15 comp. 1.83 1.2 0.1 14.65 68.8 0.102 16 comp. 1.83 1.2 2.7 14.65 68.8 0.102 17 comp. 1.83 1.2 1.31 7.5 68.8 0.102 18 comp. 1.83 1.2 1.31 21.8 68.8 0.102 19 comp. 1.83 1.2 1.31 14.65 62.5 0.102 20 comp. 1.83 1.2 1.31 14.65 75.4 0.102 21 comp. 1.83 1.2 1.31 14.65 68.8 0.04 22 comp. 1.83 1.2 1.31 14.65 68.8 0.18

TABLE 2 Conditions of carrying out the process and results thereof 2,2-DMB proportion in the total amount of hexane isomers, mass-% after after Example Process parameters 40 200 No. T, ° C. P, MPa V, hour⁻¹ Q hours hours  1 150 2.8 2.0 5.0 35.1 35.2  2 100 3.5 0.5 0.3 34.5 34.5  3 220 1.0 4.0 10.0 34.4 34.3  4 100 3.5 0.5 0.3 34.3 34.4  5 150 2.8 2.0 5.0 35.1 34.9  6 150 2.8 2.0 5.0 35.1 35.0  7 150 2.8 2.0 5.0 35.2 35.2  8 150 2.8 2.0 5.0 35.4 35.3  9 150 2.8 2.0 5.0 35.3 35.3 10 150 2.8 2.0 5.0 35.2 35.1 11 150 2.8 2.0 5.0 30.1 24.7 comp. 12 150 2.8 2.0 5.0 34.5 28.0 comp. 13 150 2.8 2.0 5.0 29.2 23.6 comp. 14 150 2.8 2.0 5.0 34.6 26.1 comp. 15 150 2.8 2.0 5.0 29.6 24.1 comp. 16 150 2.8 2.0 5.0 34.7 26.9 comp. 17 150 2.8 2.0 5.0 34.8 27.8 comp. 18 150 2.8 2.0 5.0 34.6 27.3 comp. 19 150 2.8 2.0 5.0 34.5 28.3 comp. 20 150 2.8 2.0 5.0 36.1 26.6 comp. 21 150 2.8 2.0 5.0 20.9 16.1 comp. 22 150 2.8 2.0 5.0 34.9 26.5 comp. 

1. A method of isomerization of light gasoline fractions by contacting a raw material with a catalyst containing a hydrogenating component, Group 3B, 4A, 7A and 8A metal oxides and an oxygen-containing sulphur ion, at elevated temperature and pressure, in the presence of hydrogen, characterized in that as the oxide component the catalyst contains the following composition of metal oxides: xFe₂O₃.yMnO₂.zTiO₂.nAl₂O₃.mZrO₂, with the following mole coefficient values: x=(0.06-3.6)·10⁻³; y=(0.11-2.3)·10⁻³; z=(0.12-2.5)·10⁻³; n=(7.8-21.5) 10⁻²; m=(63.3-74.7)·10⁻², and a mass ratio of said oxygen-containing sulphur ion to said composition of metal oxides is 0.042-0.178.
 2. A method of isomerization of light gasoline fractions according to claim 1, characterized in that as the hydrogenating component of the catalyst use is made of Group 8A metal: platinum and/or palladium, and/or iridium, and/or rhodium, and/or ruthenium.
 3. A method of isomerization of light gasoline fractions according to claim 2, characterized in that as the oxygen-containing sulphur ion use is made of a sulphuric acid ion.
 4. A method of isomerization of light gasoline fractions according to claim 3, characterized in that the mass ratio of the catalyst components is as follows: Group 8A metal 0.1-0.8 sulphuric acid ion >4-15 composition of metal to 100 oxides


5. A method of isomerization of light gasoline fractions according to claim 1, characterized in that the process is conducted at a temperature of 100-220° C. and pressure of 1.0-3.5 MPa, with hydrogen:raw material mole ratio of (0.3-10):1. 